1. Field of the Invention
The present invention relates generally to helicopters and other rotorcraft.
2. Description of Related Art
In simple terms, conventional helicopters have a fuselage, a main rotor, and a tail rotor. Each rotor has multiple rotor blades and is powered by an engine. Power generated by the engine is transmitted to the rotors via shafts, transmissions, and gear boxes. The main rotor is coupled to the engine via a rotor mast.
It is often desirable to have a mast with a variable angle of incidence relative to the fuselage to provide more forward thrust. There are various ways of obtaining variable mast incidence on conventional helicopters, including: (1) utilizing a tilting of the mast/transmission assembly realtive to the fuselage and engine; or (2) utilizing a tilting mast/transmission/engine assembly. Both of these options have significant disadvantages. For example, with the former, a flexible drive shaft is required; and with the latter, a complicated mounting system is required.
In addition, when the main rotor is used to provide increased forward thrust, it is often necessary to provide lift augmentation. This is often achieved by utilizing separate wings that provide lift only. Typically, helicopters with lift-augmentation wings require ancillary propulsive force from an independent device. Such helicopters are most often identified as compound helicopters.
Although great strides have been made in the area of helicopters having lift augmentation, considerable shortcomings remain.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as described herein.